The proposed research aims at the elucidation of the physical and chemical nature of a number of reactions between DNA and other macromolecules, including omega-type proteins from E. coli, Drosophila and sea urchin and to termini generating enzymes of temperate phages. Studies and also to be done on the replication of a double-stranded covalently closed DNA in vitro, in order to elucidate the basic parameters involved in replication.